Vitamin A and carotene levels of a selected population in metropolitan Washington, D. C

Mitchell, Gabrielle; Young, May; Seward, C. R.

doi:10.1093/ajcn/26.9.992

Cited by 49 publications

(12 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Vitamin A supplementation is common in the United States (5,6) and many persons consume amounts that exceed the estimated daily biological need of 800 retinol equivalents (RE) (2667 IU retinol) for women and 1000 RE (3300 IU retinol) for men (7). Because vitamin A is fat soluble and stored in the liver, deficiencies of this vitamin are seldom encountered in the industrialized world (8)(9)(10)(11)(12). Because excessive intake is potentially toxic to the liver and other tissues (5,6,13,14), vitamin A supplementation is of concern to public health officials as well as to physicians who prescribe this vitamin.…”

Section: Introductionmentioning

confidence: 99%

Safety of <7500 RE (<25000 IU) vitamin A daily in adults with retinitis pigmentosa

Sibulesky

Hayes

Prończuk

et al. 1999

The American Journal of Clinical Nutrition

View full text Add to dashboard Cite

Background: Vitamin A supplementation is being used successfully to treat some forms of cancer and the degenerative eye disease retinitis pigmentosa. The daily biological need for vitamin A is estimated to be 800 retinol equivalents ( Results: Patients in group A showed an 8% increase in mean serum retinol concentration at 5 y and an 18% increase at 12 y (P < 0.001); no retinol value exceeded the upper normal limit (3.49 mol/L, or 100 g/dL). Mean serum retinyl esters were elevated Ϸ1.7-fold at 5 y and remained relatively stable thereafter. No clinical symptoms or signs of liver toxicity attributable to vitamin A excess were detected. Conclusions: Prolonged daily consumption of < 7500 RE (< 25 000 IU) vitamin A/d can be considered safe in this age group.

show abstract

Section: Introductionmentioning

confidence: 99%

Safety of <7500 RE (<25000 IU) vitamin A daily in adults with retinitis pigmentosa

Sibulesky

Hayes

Prończuk

et al. 1999

The American Journal of Clinical Nutrition

View full text Add to dashboard Cite

show abstract

“…The increased fasting plasma vitamin A concentrations, in which delayed clearance of retinyl esters in chylomicron remnants could play a role, may be circulating in. plasma unbound to retinol-binding protein (72)(73)(74)(75), Unbound vitamin A has potential adverse effects on cell membrane stability, and is thought to be related to some of the clinical manifestations of vitamin A toxicity (76,77). Although greater fasting plasma vitamin A concentrations in the aged is consistent with the hypothesis that older humans have greater endogenous vitamin A reserves than younger humans, further research is required to determine whether these findings represent a normal response to aging.…”

Section: Discussionmentioning

confidence: 99%

Postprandial plasma retinyl ester response is greater in older subjects compared with younger subjects. Evidence for delayed plasma clearance of intestinal lipoproteins.

Krasinski¹,

Cohn²,

Ej³

et al. 1990

J. Clin. Invest.

141

View full text Add to dashboard Cite

Postprandial vitamin A and intestinal lipoprotein metabolism was studied in 86 healthy men and women, aged 19-76 yr. Three independent experiments were carried out. In the first experiment, a supplement dose of vitamin A (3,000 retinol equivalents [RE]) was given without a meal to 59 subjects, aged 22-76 yr. In the second experiment, 20 RE/kg body wt was given with a fat-rich meal (1 g fat/kg body wt) to seven younger subjects (aged < 50 yr) and seven older subjects (aged 50 yr). In both experiments, postprandial plasma retinyl ester response increased significantly with advancing age (P < 0.05).In the third experiment, retinyl ester-rich plasma was infused intravenously into nine young adult subjects (aged 18-30 yr) and nine elderly subjects (aged 60 yr), and the rate of retinyl ester disappearance from plasma during the subsequent 3 h was determined. Mean (±SE) plasma retinyl ester residence time was 31±4 min in the young adult subjects vs. 57±8 min in the elderly subjects (P < 0.05). These data are consistent with the concept that increased postprandial plasma retinyl ester concentrations in older subjects are due to delayed plasma clearance of retinyl esters in triglyceride-rich lipoproteins of intestinal origin. (J. Clin. Invest. 1990. 85:883-892.) retinyl ester * retinol * vitamin A * triglyceride-rich lipoprotein * chylomicron * atherosclerosis

show abstract

“…Previous studies in stillborn infants and short-lived term neonates from the United States and Canada have reported a mean liver vitamin A concentration of approximately 40 ~lg/g of tissue (6,14,15). Studies in preterm neonates from Brazil, Thailand, and India have reported mean liver vitamin A concentrations ranging from 16-33 ~lg/g of tissue (16)(17)(18).…”

Section: Chemical Procedures Serum Vitaminmentioning

confidence: 99%

Liver Vitamin A Reserves of Very Low Birth Weight Neonates

1985

View full text Add to dashboard Cite

ABSTRACT. This study assessed the liver vitamin A concentrations at birth in a group of very low birth weight neonates (n = 25) ( Recent studies have shown that the plasma concentrations of vitamin A (retinol) and RBP at birth are lower in neonates of preterm gestation than in infants born at term (1-3). Estimation of the vitamin A content of the liver is believed to be a more accurate indicator of the vitamin A status than the plasma concentrations of vitamin A or RBP (4, 5). This study was designed to assess the liver vitamin A reserves at birth in a group of VLBW neonates dying within 24 h of birth, prior to possible changes in vitamin A status induced by postnatal nutritional manipulation or therapeutic intervention. MATERIALS AND METHODSSubjects. Liver tissue samples were obtained at autopsy from 25 neonates who died in the neonatal intensive care unit at Vanderbilt Medical Center. These infants (male = 14, female = 11) were 16-32 wk gestational age (mean f SD; 25.6 + 3.5 wk) Eighteen infants were born within the hospital; the remainder were transferred from other hospitals within 4 h of birth. Eighteen infants were white; the remainder were black. None of the infants had congenital anomalies or evidence of intrauterine growth retardation. Death was secondary to complications of extreme prematurity and occurred within 24 h of birth in all cases. Massive intraventricular hemorrhage was the predominant cause of death. None of the infants received exogenous vitamin A during their brief postnatal life.Autopsyprocedures. Permission for a full autopsy was obtained from the parents in each case. The autopsy was performed within 12 h of death in all cases. Liver vitamin A concentrations are reported to remain unchanged in autopsy specimens for long periods, even after partial tissue autolysis (4). Liver tissue was obtained from the central portion of the right lobe. This portion was selected for analysis as it best reflects values for vitamin A concentration obtained from whole liver homogenates (6). The tissue was placed in a labeled, tightly capped plastic container protected from direct light and frozen at -20" C until analysis. The analyses were performed within 2 wk of obtaining each sample. Storage for an extended period of time at below O" C temperatures has been shown to cause no alteration in the tissue vitamin A content (7). A blood sample was collected from 16 of these infants at autopsy by direct cardiac puncture. The serum was separated from each sample by centrifugation and stored at -20" C until analysis. concentrations of liver vitamin A, serum vitamin A, and serum RBP showed no significant differences with respect to sex or race, nor did they correlate significantly with gestational age or birth weight. Linear regression analysis did not show a significant Chemical procedures. Serum vitamin

show abstract

Vitamin A and carotene levels of a selected population in metropolitan Washington, D. C

Cited by 49 publications

References 20 publications

Safety of <7500 RE (<25000 IU) vitamin A daily in adults with retinitis pigmentosa

Safety of <7500 RE (<25000 IU) vitamin A daily in adults with retinitis pigmentosa

Postprandial plasma retinyl ester response is greater in older subjects compared with younger subjects. Evidence for delayed plasma clearance of intestinal lipoproteins.

Liver Vitamin A Reserves of Very Low Birth Weight Neonates

Contact Info

Product

Resources

About